Gov. Tom Wolf and the state attorney general want the Commonwealth Court to force the University of Pittsburgh Medical Center and rival Highmark Inc. into arbitration to settle lingering disputes.

A court filing was announced Monday after UPMC said it was canceling its Medicare contract with rival Highmark, which could cause about 180,000 seniors in western Pennsylvania to lose in-network access to UPMC hospitals and doctors next year.

UPMC has said Highmark refused to pay contracted rates at the Hillman Cancer Center in Pittsburgh, but Highmark contends the cancellation was leverage to force it to drop litigation over cancer drug increases proposed by UPMC.

Based on their responses to Wolf's move, it's clear the sparring medical giants don't agree on much.

"We believe it's important that the state enforce the consent decree and protect vulnerable populations like seniors, and we think the Governor's statement with regard to UPMC's decision against seniors speaks for itself," Highmark spokesman Aaron Billger said.

There already is a consent decree, a state-mediated agreement, to protect customers after UPMC refused to extend its in-network provider agreement with Highmark effective Jan. 1. UPMC did that after Highmark acquired seven hospitals from Erie to Pittsburgh. UPMC has said that makes Highmark -- which had previously been just an insurance company -- a rival provider to UPMC, which also has its own health insurance products.

"While UPMC agrees with the allegation as to Highmark, a careful review clearly demonstrates there's no substantive or legal basis for any of the Commonwealth's misinformed claims against UPMC," Wood said.

UPMC also disagrees with arbitration, saying the consent decree already requires it and that Highmark has "actively subverted and ultimately halted" the arbitration process.

"The termination of UPMC Medicare Advantage agreements with Highmark will not harm seniors. They can expect to enjoy the benefits of more choice and competition and, likely, lower insurance premiums if they choose to stay in a Medicare Advantage plan," Wood said.